Cytochrome P450 2C19 (CYP2C19)

PG4KDS - Priority Genes

CYP2C19 is an enzyme that is responsible for breaking down (metabolizing) several of the drugs that are commonly used today. Some medications, such as clopidogrel, require activation by CYP2C19 in order for the medication to be effective. Other drugs, such as tricyclic antidepressants (e.g., amitriptyline and imipramine), are metabolized to forms that are not active and are more easily eliminated from the body. There are many other medications that may be affected by CYP2C19 (see this link

Over 20 known differences exist in the gene for CYP2C19. These differences in the CYP2C19 gene lead to the production of an enzyme that ranges from completely inactive to overactive. A system designed to classify patients into 4 metabolizer categories based on the ability of their CYP2C19 to break down drugs is used by clinicians to help guide drug therapy decisions.

Priority CYP2C19 genotypes

Routine genotypes. Most CYP2C19 medicines don’t need to be adjusted based on the following genotypes:

More information for patients...

"Do you know..." info sheet: Cytochrome P450 2C19 (CYP2C19) and medicines

More information for healthcare professionals, visit

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